The present invention relates generally to air-cooled condensing systems for steam turbine generators, and is particularly concerned with fin tubes which provide the heat transfer surface of such air cooled condensers, and methods of making such fin tubes.
Fin tubes typically comprise a central core tube through which the steam flows, and a plurality of parallel cooling fins projecting outwardly from the core tube. Cooling air is drawn over the fin tubes by a fan, and this causes cooling and condensation of the steam flowing along the core tube. Condensate is collected and returned to the steam cycle. Fin tubes are provided in rows of separate individual fin tubes, or fin tubes which are connected together by brazing or metallurgically joining the ribs of adjacent fin tubes. Alternatively, the fin tube assembly of each section of a condenser may be an integral structure in which a single set of fins extends between each adjacent pair of core tubes, with outwardly projecting fins at the ends of each fin tube section.
The core tube is typically formed from a round tube which is then flattened to form an oval or elongated cross-section. The fins are then metallurgically joined to the flattened opposite surfaces of the core tube. This technique is convenient but does not allow for easy mounting of any internal structure within the fin tube, such as the dividers in the core tubes of U.S. Pat. No. 6,332,494 of Bodas et al.